Mycobacterium tuberculosis or M. kansasii: Patients are eligible if clinical resolution of disease occurred at least 12 months prior to randomization and previously abnormal imaging studies have been normal, or stable after improvement, for at least 12 months prior to randomization. Documentation of microbiologic cure should ideally be on record. Therapy for tuberculosis or M. kansasii must have been completed at least 12 months prior to randomization.